The present invention relates to a bone locking plate, more particularly the present invention relates to a bone locking plate that includes an adjustable attachment component. Most particularly, the present invention relates to a bone locking plate that includes an attachment component whose angle relative to the locking plate may be manipulated during surgery so that it extends into the bone in a desirable orientation.
The spinal column includes over twenty bones that are coupled together. These bones are capable of twisting and curving in a variety of directions relative to one another. Traumas and developmental irregularities can result, however, in spinal pathologies for which permanent immobilization of multiple vertebrae in the spinal column is required. It is known to place a bone screw through a bone plate along an axis that has been selected by the manufacturer of the plate. See for Example U.S. Pat. No. 5,364,399, entitled "Anterior Cervical Plating System", to Lowery et al. and U.S. Pat. No. 4,484,570, entitled "Device Comprising an Implant and Screws for Fastening Said Implant to a Bone, and a Device for Connecting Two Separated Pieces of Bone", to Sutter et al. Since bone screws are known to pull out of the bone over time, these conventional bone plates have main bone-plate screws that lock down using additional loose components that either cover adjacent screws or are threaded into the head/shaft of the bone screw to prevent the screws from backing out of the bone. Often, however, the most desirable screw angle for fixing the bone screw is difficult if not impossible to determine prior to surgery.
Therefore, conventional devices have been provided that allow the user to angulate a bone screw prior to placement. See U.S. Pat. No. 5,607,426, entitled "Threaded Polyaxial Locking Screw Plate Assembly" to Ralph et al. These conventional systems, however, also include multiple loose components that must be assembled to couple the bone screw head and plate hole bearing surface. These multi-component traditional plate assemblies can be cumbersome and tedious to manipulate during surgery to achieve the most desirable angle for directing the bone screw into the patient.
What is needed is a locking plate assembly that permits polyaxial coupling of the bone screw to the locking plate and that allows high angulation as well as rigid locking plate with fewer loose pieces.
According to the present invention, a locking plate apparatus suitable for engagement with a bone is provided. The locking apparatus includes a plate with a body portion and an internal wall defining a plate hole therethrough and an expandable bushing including a radially exterior surface and an opposite interior surface defining a passageway. The exterior surface of the bushing is sized to permit rotation of the bushing about a plurality of axes within the plate hole. In addition, the locking apparatus includes an attachment component with a leading portion sized for extension through the passageway and into the bone and an opposite leading portion sized to press the bushing against the internal wall of the plate to form a friction lock between the bushing and the plate.
According to another embodiment of the present invention a locking plate apparatus is provided that is suitable for attachment with a bone. The locking plate apparatus includes a plate that has a proximal surface, a distal surface, and an internal wall that defines a plate hole extending between the proximal and distal surfaces, an expandable bushing, and an attachment component sized for extension through the bushing. The bushing includes a radially exterior surface and an opposite interior surface defining a passageway. The exterior surface is sized for insertion into the plate hole of the plate and for engagement with the internal wall to couple movably the bushing to the plate. In addition, the attachment component includes a leading portion and an opposite leading portion. The leading portion has a tapered portion that diverges away from the leading portion and is sized for pressing the bushing toward the internal wall of the plate to form a friction lock between the bushing and the plate.
Still further, in accordance with the present invention a method for coupling two bone portions together is provided. The method includes the steps of providing a locking apparatus that includes a plate having a body portion and an internal wall defining at least two plate holes through the body portion, at least two expandable bushings press fit into the respective plate holes each having a radially exterior surface and an opposite interior surface and a first end and an opposite second end defining a passageway therebetween and at least two attachment components being sized for extension into the passageway, each attachment component including opposite leading and trailing portions. In addition, the method includes the steps of positioning the body portion upon the bone portions so that the plate holes in the plate are situated over bone, rotating at least one of the bushings within the plate hole about a plurality of axes until the first and second ends of the bushing are aligned along an axis that extends through a predetermined portion of the bone. Further, the method includes the steps of inserting the leading portion of one attachment component through each passageway and driving the trailing portion of each attachment component through the respective passageway until the leading portion is positioned in the bone and the exterior surface of the bushing is pressed against the internal wall of the plate to form a friction lock therebetween.
In yet another embodiment of the present invention, a bone fixation apparatus is provided that includes a plate with a plate hole through the plate, a bone fixation screw for extension through the plate hole and into a bone, and an expansion bushing carried in the plate hole. The bushing is threaded to engage the screw and expandable by the screw frictionally to lock in position in the plate hole.
In still another embodiment of the present invention, a plate for bridging between and fixing the relative portions of bones is provided. The plate includes plate holes adjacent each bone, each plate hole carrying an expandable bushing therein for swivel movement selectively to position the axis of the bushing relative to the adjacent bone and a bone screw for penetration into the bone and expanding the bushing to lock the bushing in a selected position in the plate.
Further, according to the present invention, a plate and screw apparatus for orthopaedic applications is provided that includes a plate with a plurality of plate holes formed therein, each plate hole having an internal wall, a radially expandable bushing positioned in each plate hole to be held by said internal wall, and a screw for each plate hole, each screw having a leading portion for engaging the bushing and a trailing portion for expanding the bushing into locking engagement with the internal wall.
Additional objects, features, and advantages of the invention will become apparent to those skilled in the art upon consideration of the following detailed description of the preferred embodiment exemplifying the best mode of carrying out the invention as presently perceived.